In conventional telephone switching systems the subscribers are interconnected, inter alia, by the metal contacts of the switching grid. However, the replacement of these metal contacts by electronic switches, made possible by the progressive development of the technology of these components and by the cost reduction involved, poses problems which are mainly associated with the comparatively complicated transmission characteristics of an electronic switch. In particular, these switches have a higher resultant resistance than corresponding metal contacts, which is disadvantageous especially in multistage switching grids.
Suitable electronic switches are, for example, MOS transistors operated in the linear portion of their current-voltage characteristics.